DIY Multi Turn Hall Effect "Feedback Pot"

[Bruceaust]

Shown in this post is my successful outcome using Hall Effect Feed back.

I had problems with noisy pots ( probably because they were cheap pots ) and I decided to experiment with a Hall effect alternative.

The system I made works very well. Absolutely not noise or jitters coming from the feedback. I can now put a bit of Derivitive into my motion - and the motion produced is fantastic. - fast and accurate - rock solid ( I am please as you can probably guess )
I produced the assemblies on my CNC Router. This produced accurate alignment of the gears. Though there was a little bit of adjustment required to get the gears meshing smoothly (I used some $6 plastic gears). The Hall Effect chip is an A1302. I used salvaged bearing from a printer. Cheap neoidium magnets (ebay)I also re-used the original pots (ebay) for the drive and mounting, so it fitted back on to the motors in exactly the same way as the original pots.

I will also consider using the pot housings again to make 180 degree Hall Effect pots fo joysticks or rudder pedals, etc. (no gearing required so everything could be mounted into the pot case!)


The photos are self explanitary:

1---Multi-turn-pot-web.jpg (49.24 KiB) Viewed 17751 times

2---Disassembled-pot-web.jpg (60.33 KiB) Viewed 17751 times

3---Magnets-and-gearing-web.jpg (16.92 KiB) Viewed 17751 times

4---A1303-Hall-Effect-IC-web.jpg (42.24 KiB) Viewed 17751 times

5---Sensor-mounted-web.jpg (10.32 KiB) Viewed 17751 times

6---Exploded-Assembly-web.jpg (16.83 KiB) Viewed 17751 times

7---Rear-View-complete-web.jpg (9.15 KiB) Viewed 17751 times

8---Front-View-complete-web.jpg (10.84 KiB) Viewed 17751 times

[dervatter]

very good work....what is this material??? looking great!!

[Bruceaust]

The material is Expanded PVC, used in the sign industry etc.

[Turn]

Very ingenious, Bruceaust. Thanks for posting that.

[motiondave]

ah yes, well done, but what if you dont have a cnc machine?
Any suggestions on mounting? Or leave it to our own creativity?

[Bruceaust]

Thanks D,
Yes I am lucky to have the CNC, probably the best thing I have ever built.
Doing the gear alignment and getting the gears to mesh smoothly is the key. But using the hall effect device is really easy. If you have less than 180 deg of rotation to measure I would not hesitate to give the DIY option a try. Using those plastic shelled pots I used would be very easy. If I get a chance I will do one of those and post some pics here. Cant go wrong for about $6 outlay.

[telfel]

Hi

Can the CNC drawings / data be used to 3d Print the Parts?

Also create units with different gear ratio's to give 180, 1, 3, 5, and 10 turn input

Regards Terry

[Bruceaust]

Hi Terry,
I only used 2 1/2 D tool paths ( Profiles). I dont think they are much use for 3d printing.
I just measured the distance between the axis of the gears and made the housings to suit. ie its custom made to suit the gears i purchase from a local shop.
If you want different number of turns to equal 180deg on the hall device then it is a mater of finding a suitable gear set.

[Bruceaust]

Hi Bob,
No I don't think its a worthwhile proposition for me to make the entire unit, as its a bit of stuffing around getting it all the bits together, plus the time factor.
But I could probably cut a set of 2 Housings (the white enclosure) for about $20 plus postage. Then you could source all the other bits and do the DIY thing yourself.

Cheers,

ps. The hall effect sensors are definitely the way to go for the feedback. I have had absolutely no problems since switching to them from the "normal" wiper pots.
Even if you bought some multi turn hall effect pots, it would be an investment in the future. (though they are B expensive in Australia, hence why I went down the DIY route)

[RafBR]

viewtopic.php?f=39&t=1139&p=19559#p19559
Please someone with skills using hall sensor help over the above post